Film applicator for liquid or viscous material



July 22, 1952 T. C. PATTON FILM APPLICATOR FOR LIQUID OR VISCOUS MATERIAL Filed Nov. 4, 1948 www@ responding numbered graduations I il on Patented July 22, 1952 FILM APPLICATOR FOR LIQUID OR VISCOUS- MATERIAL Temple Chapman Patton, Mountainside, N. J., assignor to The Baker Castor Oil Company, Jersey City, N. J., a corporation of New Jersey Application November 4, 1948, Serial No. 58,272

This invention relates to film applicators, and more particularly to a device for laying down or "drawing down a thin film of liquid or viscous ymaterial of accurately predetermined thickness.

The application of films of uniform thickness on a plane surface is an important laboratory .foperation in the technology of protective coatrings. Previous methods for applying thin lms for testing and other purposes included pouring, zspinning, spraying, dipping and drawing down 'with sharp edged doctor blades. These prior methods which attempted to apply accurately predetermined thickness of lms were subject to fone or more disadvantages such as clumsiness of manipulation, lack of accuracy, readily damaged ldoctor blade, difficulty in predetermining the thickness, complicated adjustments, lack of adjustability over a range of clearances, and relquirements for attachments such as feeler gages. The film applicator of the present invention provides a sturdy device which is accurate, for. example to less than .0001 inch, has an adjustable clearance, and is read directly. The device is compact and easily manipulated. The foregoing are the essential requirements of a practical film applicator, and the device of this invention fulfills all of these requirements. j

'I'he invention is illustrated in the accompanying drawing in which a present preferred embodiment is shown, and in which- Figure 1 is a side elevational viewrof the applicator; ,Figure 2 is an enlarged plan view of the applicator with parts broken away and removed to show the' construction;

Figure 3 is a cross section taken along the line 3,- 3 of Figure 2; and

v Figure 4 is a plan view of an alternative embodiment ofthe invention. I'he film applicator consists of parts mounted on a central shaft I threaded at the respective ends 2 and 3. Mounted on the cylindrical and unthreaded portion f the central shaft I are end guide plates 4 and 5 extending radially and bilaterally with respect tothe axis of the shaft between which extends an applicator cylinder barrel 6. The cylinder 6 comprises a central aprplicating or spreading section I, shoulders and 9 near eachend of the cylinder 6, and beyond the A shoulders are gage sections I I and I 2 having corvtheir respective surfaces.

The sections 8, 9, II and I2 of the applicator cylinder barrel 6 are all cylinders developed on the axis I4, as shown in Figure 3. The central and 8 Claims. (Cl. 15-236) 2 adjustable applicating section l is developed on the longitudinal axis I5 which is eccentric With respect tothe axis I4. As shown in Figure 1, the height of the guide plates 4 and 5 is preferably approximately identical to the diameter of the cylindrical gage sections I I and I2 for registrytherewith. The diameter of the shoulders 8 and 9 is greater than the diameter of the cylindrical surfaces adjacent thereto. Lock nuts IB and II are tightened on the threaded portions 2 and 3 respectively of the shaft I. The upper surface of the eccentric cylindrical section 'I merges into the surface ofthe shoulders 8 and 9, as shown inFigures l, 2, 3 and 4, but this tangential relationship is not essential so long as the section l is of smaller diameter than, and lies Within, the diameter of the shoulders. At the opposite or spreading surface I8 of section I, a space I9 is defined between the lower portion of the cylindrical section 1 and the base surface 2 I onto which the film of material is to be applied. Bench markings 22 are provided on the Vupper faces of the guide plates.

Y vAs shown in Figure 1, the shoulders 8 and 9 always rest on the surfacev 2|. It is, of course, preferable in laying down or drawing down thin films that the surface 2l be a plane surface of glass', paperboard, enameled 'metaL polished metal, vor other smooth plane and preferably non-absorptive material.

The applicator of this invention may be used to apply films of any desired material to be tested. and is especially useful for testing the flexibility, drying time, hiding power, etc., of liquid or viscous materials, such as paints, lacquers, drying oils, varnishes, etc. Y

In'operation, the lin applicator is rst placed on a plane surface such as 2|. The lock nut I'I is loosened and the barrel 6 is rotated until a desired scale marking I3 is brought even with the bench markings 22 on the guide plates II and I2. Rotation of the barrel 6, of course, varies the distance from the lower surfaceVlS ofthe applicator section I with respect yto the base 2|. For example, when the barrel 6 is rotated 180 lfrom the position shown in Figure 1, there is no space between thesection I and the base 2l. `To take an illustrative example, the marking graduations I3 maybe so calibrated that eachnuxn- :ber adjacent thereto represents a number of mils of I clearance between., surface I8 and base 2|, thereby predetermining the thickness of material spread `or drawn down from the bank. of paint or varnishf23, as shown in Figure 3. When the desired thickness ofthe film hasthus been determined byrotation of the Abarrel for v'proper 'alone vant'agefoi `the rocking, feature Vis that so long as theidperator is able to rockl the applicator, he is x[assured that the .device is riding onthe shoulders registry of the selected marking 22, lock nut l1 is tightened and the lower surfaces 24 and 25 of the guide plates 4 and `are parallel. inasmuch as the dimension of the guide plates 4 and `5 from the center of axis I4 to the surfaces 2d and 25 is less than the radius of the shoulders 8 and `ii, Aa space 26 is provided between the surfaces 24 and 25 on the one hand, and surface 2l, on the other hand.

As shown in Figure 3, the guide plates 4 and -51 may rock slightly back and forth after the asmark I3 with the bench sembly is tightened, since the shouldersor-rockers 8 and Si` project beyond the remainder-o1" the surfaces of the applicator. This rocking feature is extremely important -in the drawing down of lms of assured accuracy. The test'material 23 is poured onto the `base 2l ,and the Aapplicator is firmly moved in the direction shown by the arrow in Figure 3, applying uniform light pressure as the applicator is moved. As the ap- .,plicator V.is -drawn along, film 21, of uniform thickness is produced. The ,fact -that the ap- Qplicator rides on the shoulders .3v andV 9 .excluv.sively ,during the .drawing ,down process insures that appreciable variationswill not occur. 'The .spaces 26 permit very slight rocking of the guide plates, but the limit of ,rotation of the .entire .ap-

plicator on its own axis It is coni-ined to .a Very .small sector .by the abutment of either end of the guide .plates againstfthe base 2l. When the graduations I3 Iare-designed for changes cfthickl*nessoi .001 inch each, the diierences in thicky nessn'f `the vspace I Q .are reduced .to approximately .lleolinch'because .of `the thinness .of the space .26, .thereby conning the rocking motion to a -very small degree. -The space 2S. has been en'- lalg'cd in. .the drawing .relative yto the actual .tolerances Vavailable, in order to illustrate theV oper- -.at ion ,of thev dev-ice. `The 'maximum error introduced by. the use vof the rocking principle has vbeen shown to .be -less than .0.08 milin thecase of a typical construction, in which .the diametergof the bearing shoulder is 0.5000 inch, the .width of theend guides is 0.49.60 inch, and the vlength of the end guides is 1.0 inch. The parts ofsthe .device in actual Ymanufacture are preferabflyrmad'e of stainless steel which has been pre- .'.cision .machine tooled to a. tolerance of .0001 inch, so that the parts snugly interfit and that vthe operating surfaces are dimensionally accurate.

, -When .using the first-described embodiment of fthc invention, i. e., where a rocker action may be imparted to .the guide platesthe rocker action maybe readily taken advantage of by the operatorfin obtaining a smooth, even ilm.v As the ,Qpfrator vdraws the applicator along the surface 2L he may lslightly twist the barrel-back and `forth' within Ythe limits permitted by the oppo- `,sitelower edges of the rockers. This avoids any tendency of the applicator to stick or catch, and assistsan even rate of travel of the applicator hefbasfe surface. Another important adaracteristicspf of1 varying thickness.'

like that shown in the iirst embodiment of the invention, except that the guide plates 32 and 33 are not identical to each other. Guide plate 32 is similar to guide plate t, but guide plate 33 is of greater height thereby permitting one end of the appicator to be raised, and thereby producing vthe filmV di of l,graduatedthickness.

n Surfaces .34 of the guide plates 32' and 33 may be at right angles to their upright walls,

.or as shown in Figure 4, they may be beveled to permit plane surface Contact with the base 2|, rather Vthan edge contact, which could scratch or deface the base. Guide plate -33 may, of

course, be substituted for guide plate 5 by dis- -assemblingthe-structure shown in Figure l, and rthen..reasseinbling In this embodiment of the invention, it .is preferred that guide plate 32 shall replace the guide plate t, for the purpose just described.

A preferred arrangement for the embodiment shown in Figure n4, i. e., to produce a Wedge vmils-'for the production ,of iilin Wedges of Vgreater thickness. f

It is obvious that, if desired, `linear variations may .be produced in the thickness of vthe film as itis being produced, by rotating the barrel while Lit is traveling to draw the film down. Films of varied predetermined.thicknessfmay .thus lbe drawn down rapidly and in avsingle operation. in fact, films having sections of -four different thicknesseshave been drawn ydown in Veight seconds total elapsed time, which vrequired three adjustments in transit.

'While' I Yhave shown and Vdescribed certain present preferred embodiments `of the invention, it is to be understood thatthe invention issusceptible of other embodiments-and constructions, and that the scope of the Vprotection afferded is to be limited ,only` in accordance with the appended claims.

V What s-claimed is:

1. A nlm applicator adaptedto produce a liquid film of predetermined thickness on a flat base, which comprises a barrelk section, rockers disposed near the ends of saidbar-rel section, and a guide having Va substantially straight lower edge extending bilaterally from the barrel secticuo. and spaced slightly from said base When in operating position, whereby the rocking movement of said rockers is restricted by theV abutment of the ends of the lower edge of said guide aga-inst the base. l

2. An adjustable film. applicator `adapted to produce aV liquid .nlm ofV predetermined thickness on a :dat surfacewhichcomprisesa cylindrical spreader, cylindrical shoulders ,extending beyond the surface of said spreader, said shoulders havinglarger diameterthan said-spreader Aand, being eccentric withrespectato saidspreader,

a guide extending radially from the aXis-fef-said '.spreader, and means or'rotatably adjusting jthe .ax-iai position-o1` said spreader with respect to said guide, Y t

3. An adjustable film applicator adapted to produce a liquid film of predetermined thickness on a fiat surface, which comprises a spreader element having a curved spreading surface and curved shoulders in fixed relation to and extending beyond said spreading surface, the curvature of said shoulders being eccentric with respect to said spreading surface, a guide extending radially with respect to the axis of said spreader, and means for rotatably adjusting the axial position of said spreader with respect to said guide.

4. An adjustable film applicator useful to lay down wet lms of predetermined thickness on a smooth surface, characterized by a barrel resting on cylindrical end shoulders which act as bearing surfaces, a portion. of said barrel between said shoulders comprising a substantially cylindrical surface of smaller cross-section than the cross-section of said shoulders and being eccentric to the axis of said shoulders, a threaded shaft extending beyond one of said shoulders and being concentric therewith, a guide plate being positioned on said threaded shaft, said guide plate being fixed in position by a locking nut fitting said threaded shaft during use of the lm applicator, said locking nut permitting change in position of the barrel relative to said guide plate when unlocked, thereby enabling the instrument to be adjusted to give a selected clearance but preventing change in position of the barrel relative to the guide plate when locked, and thereby maintaining the selected constant clearance While in use.

5. The adjustable lm applicator of claim 4 in which the circumference of the eccentric central portion of said barrel is tangential'at one point to the circumference of said end shoulders.

6. The adjustable lm applicator of claim 4, having scale markings on the unthreaded portion of its barrel adjacent to said guide plate, said markings indicating at a given, readily observable index position the shortest distance between the surface plane on which said end shoulders rest and the plane parallel thereto, passing tangent to the surface of the eccentric portion of said barrel.

7. An adjustable film applicator comprising a barrel resting on end shoulders concentric withv each other, a central shaft of reduced diameter extending from said barrel, said central shaft acting as an axis on which said barrel can be j rotated, that intermediate portion of said barrel between said shoulders being precision machine tooled in such manner that the circumference of the cross-section of said intermediate portion is a circle eccentric to the axis, said eccentric circle being smaller than and tangent at one point to the circumference ofv the smaller cross-section of said concentric shoulders, a guide plate positioned on said shaft adjacent the end of the barrel, and means for locking the guide plate with respect to the barrel.

8. The adjustable film applicator of claim 4, having both ends of said threaded shaft kextending beyond said end shoulders and two of said guide plates, said guide plates being located at opposite ends of said barrel and being positioned on the extended ends of said shaft and being substantially rectangular, the height of one of said guide plates being substantially identical REFERENCES CITED The following references are of record in the file of this patent: y

UNITED STATES PATENTS Name Date Bradley Feb. 17, 1948 OTHER REFERENCES Circular issued by the Henry A. Gardner Laboratory, Inc. and entitled Interchemical Direct Reading Wet Film Thickness Gage (Figs. 1 and 2).

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